validation of alghorithm for https://github.com/globaleaks/Tor2web-3.0/issues/217

gistfile1.py

def getBestLangMatch(accept_language, supported_lcs):
    def parse_accept_language(accept_language):
        return [l.split(';')[0] for l in accept_language.replace(" ", "").split(',')]

    def language_only(lc):
        if '-' in lc:
            lc = lc.split('-')[0]

        return lc

    for lc in parse_accept_language(accept_language):
        # returns es-PT if es-PT is available (perfect match)
        for l in supported_lcs:
            if lc.lower() == l.lower():
                return l

        lc = language_only(lc)

        # returns es if asking for es-PT with
        # es-PT not available but es available
        for l in supported_lcs:
            if lc.lower() == l.lower():
                return l

        # returns es-ES if asking for es-PT with
        # es-PT and es not available but  es-ES available
        for l in supported_lcs:
            if lc.lower() == language_only(l).lower():
                return l

    return 'en-US' # last resort

# Should return ar
print getBestLangMatch('uk,    ar;q=0.8, ur;q=0.7', supported_lc)

# Should return es-ES
print getBestLangMatch('uk, ur;q = 0.8,    es;  q=0 . 7', supported_lc)

# Should return es-ES
print getBestLangMatch('uk,ur;q=0.8,es-Pt;q=0.7', supported_lc)

# Should return es-ES
print getBestLangMatch('uk,ur;q=0.8,es-eS;q=0.7', supported_lc)

# Should return en-US
print getBestLangMatch('xx,yy;q=0.8,zz;q=0.7', supported_lc)